8^. 



EDITOR'S PREFACE. 



IN the following work Baron Liebig has given to the 

 public liis mature views on agiiculture, after sixteen 

 5'ears of experiments and reflection. The fundamental 

 basis of the work is still the so-called Mineral Theory, 

 which holds that the food of plants is of inorganic 

 nature, and that every one of the elements of food 

 must be present in a soil for the proper growth of a 

 plant. The discovery of the remarkable power of ab- 

 sorption possessed by arable soils has necessarily led to 

 a modification of the views regarding the mode in which 

 plants take up their food from the soil. As the food of 

 plants cannot exist for any length of time in solution in 

 soils, it is clear that there cannot be a circulation of 

 such solution towards the roots, but the latter must go 

 in search of food. Hence the great importance of 

 studying the ramification of the roots of plants, and 

 the mode of growth of the different classes of plants 

 cultivated by man. Tlie hrst cl)a])ter is devoted to tlie 

 consideration of the growth of plants, of the formation 

 of their roots, and of their power of selecting food, 

 and the part played by the mineral matters which are 

 absorbed. 



If the food of ])lants is not in solution in tlie ground, 



A 2 



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